Monthly Archives: January 2014

Over the years I have spent a lot of time training science presenters. I’ve seen the best part of a full spectrum: Those calm cucumbers who get up on stage without a second thought, and those who are virtually paralysed with fear. Every time.

I have learned that you can’t always tell the latter from the former with any real degree of accuracy until there are just the two of you in rehearsal before an audience walks in the door. Sometimes the cool ones crumble.

Today, I spent some time in our theatre with a new recruit who will soon start treading the boards for herself. When I started describing the different techniques to keep the jitters in check, perhaps even turn them into a positive force, she told me about this recently uploaded TED talk.

I should talk to CLEAPSS about this sometime – Andrea’s comments on gloves make a lot of sense to me, but I’ve no idea what the standing advice for schools is. Ah, the simple life of not actually being a teacher.

We can talk about maths here, right? Well hey, I guess it’s me that makes the rules, so: yes, we can talk about maths here.

You’ll have to crank up the volume, but it’s worth it: Katie Steckles‘ description of group theory and Rubik’s Cubes is as good as any I’ve seen. Better, in fact, in that for the first time in 30 years of cubing I think I understood it this time.

…and believing you understand something is the same as understanding it, yes? Oh no, wait: this site draws the line at philosophy. Drat.

Over the last few years, making all these demofilms, I’ve found myself thrust back into the world of school education. It’s a bit of a shock. I’m young enough to have taken GCSEs myself, but old enough to have been in the first year to sit them. Much has changed.

One thing I find slightly baffling is the obsession with extremely precise terminology. There’s a natural inclination to precision in the sciences, but some of what I’ve seen veers towards the obsessive. It’s not precise, it’s pedantic. And it’s nerve-wracking. I can’t write a sentence of script without the fear of somehow mis-stepping, of treading on some unseen toes and bringing down some unrelenting diatribe about how you can’t use that specific word there, only this one.

Now, I’m old enough and weary enough to battle through such pressures. There are also times when I can dimly recall enough of the physics I once did to be reasonably certain that not all of the advice I receive is… umm… correct.

But if I find myself staring at an explanation with that stomach-knotting dread of you’re doing it wrong, how is a twelve year-old supposed to cope? Respect due, we’re raising them tough these days.

My assumption is that pedantry has crept in because it’s quicker and easier to assess whether the student can recite rote-learned material accurately than it is to judge their understanding against the examiner’s (also-flawed/incomplete?) knowledge.

But that really is an assumption. So, some questions:

Am I right that school science is increasingly pedantic?

Does being able to parrot a very particular definition demonstrate understanding?

…or am I falling into the category of “people who don’t know much about education, but inexplicably think their opinion has some value anyway”?

I’m a bit of a fan of the Cambridge Science Centre, and of the people behind it. A year ago I trekked down from Newcastle to help them fix things up just before they opened. So by ‘fan’ I mean ‘groupie.’

Hence, my favourite parts of this film are Chris Lennard saying ‘Heath-Robinson‘ rather than ‘Rube Goldberg‘ (quite right too), and the brief glimpse at the end of the inimitable Dave Ansell leaning in to blow out a candle. Lovely people all.

My biggest problem with Heath Robinson machines is that they’re impossible to photograph unless they’re designed specifically for the camera. And the only people to have done that, really, are the folks behind the magnificent Japanese children’s series Pitagora Suichi, whose mechanisms are unbelievably smart:

I’ve ordered a handful of 18mm steel ball bearings for a demo that isn’t a demo, it’s merely a handling object, but handling objects can also have power and impact.

Hold out your hand and feel the weight of this ball on your palm. It’s pretty heavy. The metal is dense. Now imagine the impossible.

Imagine that all of this room is squashed and squeezed into the ball. It’s pretty tightly packed and much more dense. Now imagine the whole building is inside this ball. Hardly conceivable, but we’re not there yet. The stuff we’re made of contains lots of gaps – tiny gaps we can’t see, but gaps nonetheless. If all those gaps were filled in with more stuff we could squeeze even more mass into the ball. The whole city. The country. The entire world.

If the whole Earth, everything in it and everyone on it, were so densely packed that it could fit inside this steel ball, it would be a black hole. So dense that nothing could escape the pull of gravity.

It’s incredible how powerful something can be when brought down to an intimate, handle-able size.

The Earth has a Schwartzchild radius of 9mm. If the Earth was a black hole it would comfortably fit inside my wedding ring. That’s amazing.

Footnote: Please make sure you read Dave Ansell’s comment below. We’re not aware that any black holes the mass of the Earth exist. Black holes with larger mass would not need to be so dense.

I suspect many of you who watch the above video will know exactly how it’s done but it’s not immediately apparent to everyone, especially if you choose to present it in a way that isn’t quite honest about what’s going on.

I use this demo in my teaching to introduce the idea that an object will topple over if the line of action of its weight lies outside its base. I usually present it as a challenge: I start off with two identical (apparently) empty drink cans on my desk (yes, I know the ones in the video have slightly different designs). I offer one of the cans to a student and challenge him or her to balance it on the edge of the base. I tell them I’ll try to do the same with the other can. I make a big show of concentrating, then reveal that I have managed to make my can balance while the student’s can keeps falling over (this usually gets a gasp of approval – as I think the video shows, the can balanced on its edge looks quite disconcerting). After the initial surprise at my being able to balance the can, the students usually guess that something’s not quite right.

I think this demo works well presented as a “magic trick” because it captures students’ attention and provokes the question “what’s going on?” or “how does that work?” and that’s when the discussion begins…

UPDATE: I’ve had a couple of responses to this post on Twitter and elsewhere. I should perhaps have said that using this type of approach may not be suitable for all teachers – you have to be comfortable with the way you present a demo to a class and if showmanship isn’t your thing there’s no point forcing it (although I’d argue that this particular demo requires very little in the way of showmanship to present as a “magic” trick). We touch on this issue in our forthcoming film Demo: The Movie.

A teacher contacted me saying it was a shame I didn’t provide an explanation as it would make it easier for teachers to do the demo if they knew exactly how to do it. So, here’s the trick: place a little water in the can you want to balance before your lesson. The easiest way to judge the correct amount of water is to hold the can in the balanced position then pour water into the can until you feel it just balances. Alternatively, you could pour in liquid wax and let that set so that you have a pre-prepared can that you can keep in the equipment cupboard.

Ah, the joy of modern media. You can publish a film one week, and the following week you see a tweet from a teacher who’s incorporated ideas from it into their lesson. Even better: they post a photo of their students exploring ideas around air pressure via the approach in the film.

Photo above from Tom Sherrington, @headguruteacher. Huge thanks for allowing us to repost, Tom – it’s a delight to see this stuff getting used.